@djh said:
Yes, I was holding the mouse button and the cursor key. Have to change that habit when trying to constrain.
Yeah. Don't hold either one. Most actions with the left mouse button in SketchUp are click and release, not click and hold. There are a few exceptions but for the most part you don't hold the mouse button.
As for the cursor keys, they are a press and release. If you use Shift to constrain a move or drawing direction, you'll need to hold Shift.